The present invention relates to a method of producing parts made from plastics material by injection moulding and to apparatus for carrying out this method.
More specifically, the present invention is concerned with the production of parts made from plastics material having a small thickness.
The present invention relates in particular, but not exclusively, to the production of reflector bodies intended to be provided at a later stage with a reflective coating for signalling or lighting equipment to be used on automobiles.
Numerous methods and apparatus have already been proposed for the production of parts made from plastics material by injection of this material into a mould. However, in this case of parts having small thicknesses, it has proved difficult to ensure a perfect uniform filling of the mould with the plastics material.
As described for example in U.S. Pat. Nos. 2,999,273 and 3,906,066, it has been proposed to inject the material into a mould cavity whose volume can be varied by the displacement of a piston in the direction of the axis of injection in order to form a parison, then to move the piston closer to the opposite surface of the mould in order to compress the parison and shape each part into its final form.